create table d_table (
  d_table_id integer unsigned auto_increment primary key,
  table_name varchar(32) not null.
  d_happened timestamp not null,
  operation enum('insert','update','delete') not null,
  index (table_name, d_happened)
);

create table d_field (
  d_field_id integer unsigned auto_increment primary key,
  d_table_id integer unsigned not null,
  field_name varchar(32) not null,
  old_value text not null,
  unique index (d_table_id, field_name)
);